Salt: Too Little May Be as Risky as Too Much for Heart Health

"The findings call into question current guidelines for salt intake, which recommend less than 2.3 grams (or 2,300 mg) per day."

For years doctors have warned that too much salt is bad for your heart. Now a new study by researchers at McMaster University in Canada suggests that both high and low levels of salt intake may put people with heart disease or diabetes at increased risk of cardiovascular complications.

• Moderate salt intake was associated with the lowest risk of cardiovascular events,

• While a higher intake of sodium was associated with an increased risk of stroke, heart attack and other cardiovascular events

• And a low intake was associated with an increased risk of cardiovascular death and hospitalization for congestive heart failure.

"This research addresses an important population health issue – the association between salt intake and cardiovascular disease," says research co-leader Dr. Martin O'Donnell, an associate clinical professor at McMaster who is also appointed at the Health Research Board Clinical Research Facility, National University of Ireland.

"In general, previous observational studies have either reported a positive association, no association or an inverse association between sodium intake and heart disease and stroke. This has resulted in a lot of controversy,” Dr. O’Donnell notes.

“Our study is the first to report a J-shaped association between sodium intake and cardiovascular disease, which may explain why previous studies have found different results."

28,880 At-Risk Patients Studied

For the McMaster observational study, the researchers examined 28,880 people at increased risk of heart disease from clinical trials conducted between 2001 and 2008.

The researchers estimated 24-hour urinary sodium and potassium excretion from a morning fasting urine sample. Follow-up found more than 4,500 cardiovascular events occurred, making this one of the largest studies examining the relationship between sodium excretion (a surrogate measure of sodium consumption), as well as potassium excretion and cardiovascular events.

Extensive and careful statistical analytic methods were used to determine the association of urinary sodium and potassium with cardiovascular events, in particular heart attack, stroke, hospitalization for congestive heart failure and death.

Moderate Intake Linked to Least Risk

Compared with moderate sodium excretion (between 4 to 5.99 grams per day), the researchers found that:

• Sodium excretion of greater than 7 grams per day was associated with an increased risk of all cardiovascular events,

• And sodium excretion of less than 3 grams per day was associated with an increased risk of cardiovascular death and hospitalization for congestive heart failure.

The findings call into question current guidelines for salt intake, which recommend less than 2.3 grams (or 2,300 mg) per day.

The guidelines are mostly based on previous clinical trials that found blood pressure is lowered modestly when sodium intake is reduced to this level (which was also found in the present study).However, there are no large studies looking at whether such low levels of sodium intake reduce the incidence of heart attacks and stroke.

Sodium Guidelines for Heart Patients Should Be Clarified

Clarifying the optimal daily intake of sodium is particularly important in patients with established heart disease, as they may be especially vulnerable to the cardiovascular effects of very high- and low-salt intake and are most likely to receive recommendations on restricting sodium in their diets, the authors concluded.

"Our study confirms the association between high-sodium intake and cardiovascular disease. Our findings highlight the importance of reducing salt intake in those consuming high-salt diets and the need for reducing sodium content in manufactured foods that are high in salt," says study co-leader Dr. Salim Yusuf, MD.

"However, for those with moderate (average) intake, whether further reduction of salt in the diet will be beneficial is an open question,” he adds. “We believe that large clinical trials are the most reliable way to determine if reducing sodium intake to lower levels is of benefit."

I give up on all the salt articles on how much is too little and how much is too much because it has changed so much over the years that I'm going to use what tastes good to me and use more when I crave it badly.

When the grim reaper comes and my time is up, I don't want to think about, Oh gee, did I have too much or too little salt. With all my medical conditions it really wouldn't matter that much anyway.

It's like having reports for years that coffee would cause cancer and then finding out that it's one of the best antioxidants on earth. Go figure. I give up. Too bad I hate coffee.

I wish you others that are paranoid about salt intake good luck because I give up and really don't care anymore. I'm 59 years old and usually don't salt much of my food except for eggs and mashed potatoes, only if they need it. But when I'm in an arid and hot area, I'm going to eat potato chips or dump salt into my hand and eat it to replace what I'm losing in sweating so much.